Chancellor Merkel has denied reports of conflict over economic policy. She said the G8 discussions were based on mutual understanding, without controversy.

Officials say security issues, including concerns about Iran and North Korea, were expected to play a large part in Saturday's talks.

Mr. Obama is scheduled to hold one-on-one meetings with British Prime Minister David Cameron, Chinese President Hu Jintao and South Korean President Lee Myung-bak, among others.

The countries in the G20 account for 90 percent of global economic output and 80 percent of world trade. In addition to the G8 nations - the United States, Britain, France, Germany, Italy, Japan, Canada and Russia - the larger G20 includes Brazil, China, Indonesia, Mexico, Argentina, Australia, India, Saudi Arabia, South Africa, South Korea, Turkey and the European Union.